Crystallinity and mechanical properties of optically pure polylactides and their blends

Nonisothermal solidifications of medical-grade polylactides were conducted on compression molding sheets, resulting in a variety of crystalline forms and different amounts of crystallinity. Both optically pure polylactides, poly (L-lactide) (PLLA) and poly (D-lactide) (PDLA), were found to crystallize at a low melting temperature α crystalline form. PLLA/PDLA blends were found to yield both α homocrystallites and 50°C higher melting temperature stereocomplex crystallites. The effects of processing conditions and blend composition on crystal heterogeneity and degree of crystallinity were studied. Tensile tests reveal for these polylactides Young's modulus values of 3.5–4.2 GPa, strength values of 62–71 MPa, and elongations at break of 1–5%, depending on blend composition and crystallinity. POLYM. ENG. SCI. 45:745–753, 2005. © 2005 Society of Plastics Engineers

[1]  R. Jerome,et al.  Stereocomplexation and morphology of polylactides , 1995 .

[2]  D. Grijpma,et al.  Chain entanglement, mechanical properties and drawability of poly(lactide) , 1994 .

[3]  Y. Ikada,et al.  Crystal structure of stereocomplex of poly(L-lactide) and poly(D-lactide) , 1991 .

[4]  Yoshito Ikada,et al.  Stereocomplex formation between enantiomeric poly(lactides) , 1987 .

[5]  P. de Santis,et al.  Molecular conformation of poly(S‐lactic acid) , 1968, Biopolymers.

[6]  C. Chen,et al.  Preparation and characterization of biodegradable PLA polymeric blends. , 2003, Biomaterials.

[7]  D. Pichora,et al.  Biodegradable Polymers for Orthopedic Applications , 1993 .

[8]  O. Böstman,et al.  Absorbable devices in the fixation of fractures. , 1996, The Journal of trauma.

[9]  Y. Ikada,et al.  Biodegradable polyesters for medical and ecological applications , 2000 .

[10]  A. Pennings,et al.  High impact strength as-polymerized PLLA , 1992 .

[11]  S. Gogolewski,et al.  Enhancement of the mechanical properties of polylactides by solid-state extrusion. I. Poly(D-lactide). , 1996, Biomaterials.

[12]  Y. Ikada,et al.  Stereocomplex formation between enantiomeric poly(lactic acid)s. 7. Phase structure of the stereocomplex crystallized from a dilute acetonitrile solution as studied by high-resolution solid-state carbon-13 NMR spectroscopy , 1992 .

[13]  P. Törmälä,et al.  Biodegradable self-reinforced composite materials; manufacturing structure and mechanical properties. , 1992, Clinical materials.

[14]  R. Vasanthakumari,et al.  Crystallization kinetics of poly(l-lactic acid) , 1983 .

[15]  Yoshito Ikada,et al.  Stereocomplex formation between enantiomeric poly(lactic acid)s. XI. Mechanical properties and morphology of solution-cast films , 1999 .

[16]  H. Fritz,et al.  Plasticizing polylactide—the effect of different plasticizers on the mechanical properties , 1999 .

[17]  T. Masuko,et al.  Crystallization behaviour of poly(l-lactide) , 1998 .

[18]  A. Schindler,et al.  Polylactide. II. Viscosity–molecular weight relationships and unperturbed chain dimensions , 1979 .

[19]  K. Diederichs,et al.  Mechanism of the Stereocomplex Formation between Enantiomeric Poly(lactide)s , 1996 .

[20]  I. C. Mcneill,et al.  Degradation studies of some polyesters and polycarbonates—2. Polylactide: Degradation under isothermal conditions, thermal degradation mechanism and photolysis of the polymer , 1985 .

[21]  Yoshito Ikada,et al.  Stereocomplex formation between enantiomeric poly(lactic acid)s. 4. Differential scanning calorimetric studies on precipitates from mixed solutions of poly(D-lactic acid) and poly(L-lactic acid) , 1991 .

[22]  Y. Ikada,et al.  Stereocomplex formation between enantiomeric poly(lactic acid)s. 3. Calorimetric studies on blend films cast from dilute solution , 1991 .

[23]  J. Runt,et al.  Crystallization and Microstructure of Poly(l-lactide-co-meso-lactide) Copolymers , 1998 .

[24]  J. Feijen,et al.  Stereo block copolymers of L- and D-lactides , 1990 .

[25]  Y. Ikada,et al.  Stereocomplex formation between enantiomeric poly(lactic acids). 9. Stereocomplexation from the melt , 1993 .

[26]  Katrin Mackenzie,et al.  Thermal decomposition of biodegradable polyesters—II. Poly(lactic acid) , 1996 .

[27]  S. Gogolewski,et al.  The effect of thermal treatment on sterility, molecular and mechanical properties of various polylactides. I. Poly(L-lactide). , 1996, Biomaterials.

[28]  M. Doxastakis,et al.  Synthesis and properties , 1999, Journal of materials science. Materials in medicine.

[29]  J. Kohn,et al.  Physico-mechanical properties of degradable polymers used in medical applications: a comparative study. , 1991, Biomaterials.

[30]  J. Sarasua,et al.  Crystallization and melting behavior of polylactides , 1998 .

[31]  Catia Bastioli,et al.  Effect of molecular weight and crystallinity on poly(lactic acid) mechanical properties , 1996 .

[32]  A. Södergård,et al.  Properties of lactic acid based polymers and their correlation with composition , 2002 .

[33]  P. Törmälä,et al.  Processing and characterization of absorbable polylactide polymers for use in surgical implants. , 1994, Journal of Applied Biomaterials.